Hugely enhanced flame retardancy and smoke suppression properties of UHMWPE composites with silicone‐coated expandable graphite

Abstract

In this paper, silicone‐coated intumescent flame retardants was prepared by an efficient and simple approach, aiming at enhancing the flame‐retardant efficiency and smoke suppression properties. The surface of expandable graphite (EG) was treated prior to the coverage of nonflammable silicone. The resultant silicone‐modified EG hybrid (SEG) was combined with ammonium polyphosphate (APP) and applied as a flame‐retardant and smoke‐suppressant for ultrahigh molecular weight polyethylene (UHMWPE). Compared with UHMWPE/APP/EG (with 15 wt% APP/EG), UHMWPE/APP/SEG (with 15 wt% APP/SEG) gives decrement by 18.5% in the peaks of the heat release rate, 6.33% in total heat release and 13.6% in total smoke release, whereas increment by 23% in tensile strength and 12.1% in elongation at break, respectively. It is suggested that the introduction of silicone on the surface of EG can improve the interfacial compatibility between EG and UHMWPE. Moreover, it can lead to forming more char residue and reducing the release of smoke particulates during combustion process of the composites.

Expandable Graphite for Flame Retardant PA6 Applications

“…PA6/EG formulations provided excellent results in cone calorimeter and LOI test, though showed less efficiency in UL-94 tests. As it has been reported for other polymeric systems, the general mode of action was also found to be exclusively physical, resulting in a lower burning rate, lower smoke production and a significant drop of the pHRR and THE (e.g., [14,16,40]). No changes in gas phase decomposition products were found confirming a purely physical expansion mode with no chemical interactions between polymer and filler.…”

“…This effectively slows or stops fire spread by impeding thermal heat feedback from the flame to the substrate, migration of oxygen to the surface, and mass transfer of low molecular weight decomposition products to the gas phase. [ 5 ] Despite proven efficiency as a flame retardant in various thermoplastic polymer systems (e.g., PP [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ], PE [ 13 , 14 , 15 , 16 ], ABS [ 17 ], EVA [ 18 , 19 ], PET [ 20 , 21 ], PS [ 22 ], PVC [ 23 ]), the industrial use of expandable graphite is limited to niche applications. One of the reasons is the low temperature stability of commercially available expandable graphite grades, with maximum processing temperatures typically lower than 230 °C; only some literature is available focusing on this topic [ 20 ].…”

A Synergistic Flame Retardant System Based on Expandable Graphite, Aluminum (Diethyl-)Polyphospinate and Melamine Polyphosphate for Polyamide 6

“…Within this paper we discuss an efficient multi-material flame retarding system for polyamide 6 based on expandable graphite (EG) as main ingredient as well as AlPi/MPP mixtures as synergistic component. EGs have been proven to be an excellent flame retardant additive in various polymers as individual component and as multi-material flame retardant system, e.g., PE [ 10 , 11 , 12 , 13 ], PP [ 14 , 15 ], PS [ 16 ], PVC [ 17 ], ABS [ 18 ], PA6 [ 19 ]. When a critical temperature is reached, blowing agents intercalated between the graphene layers react, forming a voluminous and thermally stable char-residue with a typically worm-like structure.…”

Flame‐retardant, phosphorous‐based polyurethane triazoles via solvent‐free and catalyst‐free azide–alkyne cycloaddition and their cure kinetics

“…Development of phosphorous‐based flame retardants (FRs) is a promising area of research as they function as alternatives to halogenated FRs 1 because halogenated FRs are toxic and release acidic fumes on the ignition and are also difficult to recycle 2 . In addition to phosphorus‐based FRs, nitrogen‐based FRs, 3 boron‐based FRs, 4,5 silicon‐based FRs, 6,7 metal hydroxide–based FRs, 8,9 and biochar 10 are widely used as nonhalogenated FRs. Recently, graphitic carbon nitride (g‐C 3 N 4 ) and MXene hybrids have attained much interest as nonhalogenated FRs owing to their 2D packing structure and excellent thermal stabilities 11‐13 .…”